Field of the Invention
The present disclosure relates to a stereoscopic image display, and more particularly, to a polarization glasses type stereoscopic image display, which can improve the vertical viewing angle of a stereoscopic image.
Discussion of the Related Art
A stereoscopic image display displays a stereoscopic image by using a stereoscopic technique or an auto-stereoscopic technique.
The stereoscopic technique, which uses a binocular parallax image between left and right eyes of a user and has a high stereoscopic effect, includes a glass method and a non-glass method which have been put to practical use. In the glass method, the binocular parallax image is displayed on a direct view-based display device or a projector by changing a polarization direction or in a time division manner, and polarization glasses or liquid crystal shutter glasses are used to implement stereoscopic images. In the non-glass method, generally, an optical plate such as a parallax barrier or the like for separating an optical axis of the binocular parallax image is provided at the front surface or rear surface of a display screen.
FIG. 1 is a view showing a prior art polarization glasses type stereoscopic image display.
Referring to FIG. 1, the glasses type stereoscopic image display 1 comprises a display panel and a patterned retarder 17 bonded to the display panel.
The display panel comprises a thin film transistor array substrate 10, a color filter substrate 12 comprising color filters 13 and a black matrix 14, and a liquid crystal layer 15 formed between the thin film transistor array substrate 10 and the color filter substrate 12, a second polarizing plate 16b attached to the bottom of the thin film transistor array substrate 10, and a first polarizing plate 16a attached to the top of the color filter substrate 12.
The patterned retarder 17 comprises a first retarder pattern for selectively transmitting only first polarized light and a second retarder pattern for selectively transmitting only second polarized light, and is attached on the first polarizing plate 16a. The first retarder pattern and the second retarder pattern are formed alternately line by line, and a surface-treated protective film 18 may be attached on the patterned retarder 17.
The stereoscopic image display 1 of this type alternately displays a left image and a right image and switches polarization characteristics incident to polarization glasses via the patterned retarder 17. Thereby, the glasses type can implement stereoscopic images by spatially dividing left images and right images.
The polarization glasses type stereoscopic image display may suffer 3D crosstalk depending on a viewing position when displaying a stereoscopic image. 3D crosstalk occurs when a left-eye image and a right-eye image are seen overlapping each other by a single eye (left-eye or right-eye). When viewing the display panel from the front, the left-eye image is transmitted and seen through the corresponding first retarder pattern alone, and the right-eye image is transmitted and seen through the corresponding second retarder pattern alone, whereby no 3D crosstalk is perceived. However, when viewing the display panel from a vertical direction, the left-eye image may be transmitted through the first retarder pattern and the second retarder pattern corresponding to the right-eye image and seen mixed with the right-eye image, and the right-eye image may be transmitted through the second retarder pattern and the first retarder pattern corresponding to the left-eye image and seen mixed with the left-eye image, whereby 3D crosstalk is perceived.
In general, a vertical viewing angle on a stereoscopic image display is defined as the sum of upper and lower viewing angles at which 3D crosstalk is perceived with a probability of 10% or less. The vertical viewing angle is closely related to the width of black matrices, the distance between the color filters and the patterned retarder, and so on. By increasing the width of black matrices, 3D crosstalk may be improved and vertical viewing angle may be widened, but aperture ratio and luminance may be lowered.
The prior art polarization glasses type stereoscopic image display has attained a desired vertical viewing angle by increasing the width of black matrices in spite of low aperture ratio and luminance.